Method of manufacturing lock nuts



Dec. 31, 1940. R. w. LUCE 2,226,935

METHOD OF MANUFACTURING LOCK NUTS Filed Feb. 2, 1939 2 Sheets-Sheet 2 .0Mia Q f 3b L a I INVENTOR P/(HAPD W. LUCE Patented Dec. v 31, 1940UNITED STATES PATENT OFFlCE Richard Waterman Luce, Westfield, N. J.

Application February 2, 1939, Serial No. 254,215 In Great Britain August16, 1938 6 Claims. (Cl. 10-86) The invention herein disclosed relates toa from bar stock, preferably bar stock having the method for making alock nut of the type disrequisite polygonal configuration. The piece ofclosed in the copending application Serial No. bar stock utilized forthe nut is of the same 167,757, filed October 7, 1937, for Lock nut.length as the finished nut when the resilient sec- The lock nutdisclosed in theaforementioned tion is expanded, as for example beforethe 5 application is preferably constructed from a sinlocking section iscompressed. In accordance gle piece of metal and consists of threeportions, with the method the bar stock is first drilled a tapped bodyportion having the load carrying longitudinally. The bellows-likeresilient porthreads, a smaller tapped portion displaced from tion ofthe nut is next formed through an inthe body portion and a bellows-likeresilient porternal recessing and external form cutting op- 10 tionbetween the tapped portions. The bellowsoration. like resilient portionconsists of two, axially dis- This method of manufacturing the nut mayplaced, substantially radial wall sections joined be carried out on anautomatic screw machine at their outer circumferential edges in a curvedhaving several stages. The recessing operation circumferential wallsection. The threads of the y be completely performed in a single stage.15 tapped portions are interrupted at the resilient However, the lengthof the internal recessing portion and are normally out of phase suchthat tool including the thickness of the shank can when a bolt entersthe nut it causes the resilient not, of course, exceed the drilled hole.In consebellows portion to expand and thus, the load carq ce. tOOlSuitable c p e e rerying threads of the body portion are caused tocessing operation is rather delicate in relation 20 engage the threadsof the bolt in frictional ento the amount of metal to be removed and thegagement. The frictional force between the tool cannot be crowded.Because of this fact, the threads effectively maintains the nut on themachine is P ed by the recessing Operation and bolt against theloosening action of forces or m terially sl w w a si e r i s p 5vibration. tion is utilized. For this reason, the recessing is Thepresent invention has for an object to Preferably done in Several Stagesas t e 8 1 5 rotide a method to facilitate the making of such f metal obe r m v i rel i n to the size f lock nuts from a single piece of metal.a tool is too great to accomplish the recessing at Suggestions have beenmade to form the belhigh speed with a single tool and single recessinglows-like resilient portion of such lock nuts by a operation. When donein several stages, the 30 pressing operation in which a long cylindricalfirst stage may be performed with a stubby tool section is forced into abellows-like section. Such which removes a considerable Portion f t e anoperation requires a metal having extreme a n t e n t St -8e. ore of.the mot l is characteristics of free workability. Few metals, removed,and in the third stage, which may be if any of the type suitable fornuts that are mathe last. another portion of metal is removed and 35chined from bar stock, possess the characteristics the depth of therecess is len thened. The raof workability to such an extent. In tact,such d depth f the u y each o he sev ral remetalsas possess thecharacteristic of workability cessing 110015 is balanced in accordancewith the do not possess the characteristic of free ma- Stem diameter 0ft 11001- A Suitable a chinability or'of satisfactory elasticity. For ament f a hr stage op r i i o h ve the 40 lock nut of the type described,particularly for fi t t effect approximately y Percent Of the commercialproduction of such nuts, a comthe depth of the the next 9001 effectthirty promise must be made in the manufacture such percent and thefinal tool the remaining twenty that it is suitable to the metalscommonly used e t- The te configuration of t e re- 5 for nuts that aremachined from bar stock. Sment Portion is i01111811 y an external formSuch metals have the characteristic of free macutting 15001- chinabilityand the characteristic of workability when so formed, the nut is pp e lto a limited extent. The method of manufacturbeing run through t w tap dport ons. th ing such lock nuts herein disclosed provides for bodyPortion and t e Smaller t pp Port 60 the characteristics of the metalsand by virtue The nut is then pressed axially such that the of themethod nuts having the desired characbellows-like resilient portiontakes a set with the teristics of strength in the tapped portions andthreads of the two portions discontinuous or out resiliency in theresilient portions may be manuof phase an amount sumcient to take careof the factured commercially. thread tolerances of the bolts, andprovide a The method comprises forming the lock nut frictional lockingforce.

stood from the following explanation thereof specifically applied to thelock nut and tools 11- lustrated in the accompanying drawings in which:

Fig. 1 is an isometric view of the lock nut; Fig. 2 is a longitudinalsection of the finished nut;

Fig. 3 is a longitudinal section of the nut prior to the tappingoperation;

Fig, 3A is a longitudinal elevation of a recessing tool and Fig. 3B isan end view of the same; Fig. 4A is a longitudinal elevation of anotherrecessing tool and Fig. 4B is an end view of the same; and

Fig. 5A is a longitudinal elevation of another recessing tool and Fig.5B is an end view of the same.

The nut illustrated in the drawings includes a body portion l, asmaller'portion 2 axially displaced from the body portion and abellows-like resilient portion 3 between the portions I and 2. In thefinished nut the portions l and 2 are internally threaded, the threadsof the body portion I being the load carrying threads of the nut.

The nut is made from a single piece of bar stock such as hexagonal barstock. In the first operation, the bar stock is drilled to form the 39hole 4 through the nut. After the drilling operation the internalrecessing of the bellows-like, resilient portion 3 is effected. This isaccomplished, particularly in the smaller sized nuts, in three stages.The first stage of the internal recessing operation is performed by atool 5 as illustrated in Figs. 3A and 3B. The tool 5 includes a shank Sothat is undercut at 5b and a cutting portion 50 at the undercut sectionof the shank. The cutting face of the tool is at 5d. The length 5e ofthe tool is slightly less than the diameter of the hole 4. The tool isentered in the hole 4 from the smaller end of the blank and "when at theproper axial position it is moved diametrically to effect that portionof the recessing indicated by the line 30.

The cutting section of the tool 5 is shaped as shown and includes theangular sections 5! and 59. These form conical surfaces la and 2a of thesame angle as the thread angle at the junc- 50 ture of the body portionI and the resilient portion and at the juncture of the smaller tappedportion 2 and the resilient portion. This conical surface at thejuncture of the resilient portion and at the smaller tapped portionprovides a smooth conical surface to engage the end of a bolt enteringthe nut. Upon entering the smaller tapped portion of the nut, a boltmust expand the resilient portion until the threads thereof come intocorrespondence with the threads of 50 the bolt. Unless such a bearingsurface be provided, the plating on the end of a plated bolt may beinjured.

The next stage of the recessing operation is performed by a tool 6 suchas that illustrated in 5 Figs. 4A and 4B. This is similar to the tool 5.The overall length 6a of the tool is the same as the tool 5 but thecutting portion 6b is of greater length and the section of the shank isof correspondingly lesser thickness. This tool 5 effects a cut asindicated by the line 3b. The final recessing stage is performed by thetool I .illustrated in Figs. 5A and 5B. The cutting portion Ia of thistool is, of course, longer than the tool 6 and the undercut section lbof the shank is: nec- 7 essarily thinner as the overall length of thetool suiilcient to provide clearance.

\ is the same as the preceding tools. This tool removes the portionindicated by the lines 30. It will be noticed that the tool 5 effectsapproximately fifty percent of the depth of the cut required to be madein the recessing to form the 5 resilient portion, the tool 6 effectsapproximately thirty percent and the tool I efiects approximately twentypercent; and the feed of the tools per revolution of the stock islikewise progressively less. 10

The cutting faces of the successive tools 5, 0 and I are successivelynarrower an amount just Thus, when the tool 6 enters the recess, it doesnot rub against the walls of the portion cut by the tool 5. Like- 15wise, the tool I does not rub against the walls of the portions out bythe tools 5 and 6. The out eifected by the angular section 5! of thetool 5 in addition to providing the inclined surface on the nut providesa space such that a fillet, such 20 as the fillet lid on the tool 6 andthe fillet 1c on the tool 1, may be used on these tools. These filletsadd greatly to the strength of these tools so that the cutting speed maybe correspondingly increased. The ends of the tools are so shaped 25that the juncture of successive cuts is curved; there are no sharpedges. Although it has not been illustrated in detail, it will beunderstood the tools are properly backed off for cutting clearances inaccordance with the common prac- 30 tioe.

While the recessing of the resilient portion is being accomplished thestock may also be formed externally. Preferably, though not necessarily,the bar stock is roughed down to cylindrical 35 shape of a diametersubstantially equal to the external diameter of the resilient portion.An external form cutting tool may then be used to form the externalsurface of the resilient portion 3 and the smaller tapped portion lsimulta- 40 neously. The external walls of the resilient section are cutat an angle of approximately five degrees to the diameter. The innersurface of the walls follow this inclination in steps as illustrated,the illustration being of course greatly ex- 45 aggerated. In thefinished blank the walls of the resilient portion are of substantiallyuniform thickness. Preferably the outer and inner curvature of thecircumferential portion of the resilient portion 3 are concentric. .Thebroken lines 50 8 on the blank illustrated in Fig. 3 indicate the rootdiameter of the threads which are cut in the blank. After the blank istapped, it is compressed axially so as to take a set with the walls ofthe resilient section substantially parallel and 55 radial to the axisand with the threads of the two tapped portions out of phase.

The compression of the nut is gauged from the shoulder of the bodyportion. From a commercial standpoint it is impractical to maintain anthe overall length of the nut sufilciently accurate to gauge the extentof compression of the bellows-like resilient portion. However, inaccordance with this method, the outside of the bellowslike resilientportion and the smaller tapped por- 5 tion are cut by a single toolsimultaneously. The distance, therefore, between the edge of the bodyportion and the end of the smaller tapped portion is the same withinclose tolerance for all nuts of the same size. In compressing thebellows-like 70 resilient portion, a cup-shaped collar is fitted overthe smaller tapped portion and the resilient portion of the nut iscompressed until the edge of the collar engages the adjacent edge of thebody portion.

After the nut has been so formed, it may be heat treated or casehardened. This adds greatly to the tensile strength and to theresiliency of the bellows-like resilient portion.

From the foregoing, it will be apparent that by the invention hereindisclosed there is-provided a method for manufacturing lock nuts of thetype specified by which such lock nuts may be made at high speed andeconomically. Likewise, lock nuts made by this method will be uniforminsofar as the torque required to rotate a nut on a bolt is concerned.

It will be obvious that various changes may be made by those skilled inthe art in the steps of the method and the details thereof within theprinciple and scope of the invention as expressed inthe appended claims.

I claim:

1. The method of manufacturing a lock nut having two spaced tappedportions and a resilient bellows-like portion therebetween, which methodcomprises forming the resilient portion of the nut by an internalrecessing operation performed in a plurality of stages and an externalform cutting operation, tapping the nut, and compressing the nut tocause the resilient portion totake a set with the threads of the twotapped portions out of phase.

2; The method for manufacturing a lock nut having two spaced tappedportions and a resilient bellows-like portion therebetween, which methodcomprises forming the resilient portion of the nut by an internalrecessing and an external form cutting operation, simultaneously withthe external form cutting operation ofthe resilient portion externallyform cutting one of the two tapped portions, and compressing the nutaxially to cause the resilient portion to take a set with the threads ofthe two tapped portions out of phase.

3. The method for manufacturing a lock nut having a tapped body'portion,a smaller tapped portion and a bellows-like resilient portiontherebetween, which method comprises forming the resilient portion ofthe nut by an internal recessing and an external form cutting operation,forming the exterior of the smaller tapped portion by an external formcutting operation,'maintaining the distance from the edge of the bodyportion adjacent the resilient portion and the edge of the tappedportion accurately, and compressing the nut axially an amount determinedby the distance from the end of the smaller tapped portion to theadjacent edge of the body portion.

4. The method for manufacturing a lock nut having a tapped body portion,a smaller tapped portion and a bellows-like resilient portiontherebetween which method comprises forming the resilient portion by aninternal recessing and external form cutting operation, simultaneouslyex-- having two spaced tapped portions and a resilient portiontherebetween, which method comprises internally recessing the resilientportion of the nut, extemaliy form cutting the resilient portion and oneof the tapped portions with a single form-cutting tool, and compressingthe nut in accordance with a gage arranged to determine the distancefrom the tapped portion cut with the form-cutting tool to the othertapped portion.

6. The method of manufacturing a lock nuthaving two spaced tappedportions and a resilient bellows-like portion therebetween, which methodincludes the stepof forming the resilient portion of the nut by aninternal recessing operation performed in a plurality of stages and anexternal form-cutting operation.

RICHARD W. LUCE.

